The present invention relates to a head set positioning device for firmly engaging the handlebar stem, the upper head set, the head tube and the lower head set.
A conventional bicycle head set is shown in FIG. 6 and generally includes front fork stem 10 extending through the head tube 30 of a bicycle and an upper head set 400 is mounted to a top end of the head tube 30. A handlebar stem 13 is mounted on the front fork stem 13 and a lower end of the handlebar stem 13 presses on an pressing ring 78 which positions the upper head set 400 in position by a downward force. A disk 75 is located in the handlebar stem 13 and a bolt 74 extends through the disk 75 and a first pushing member 77 threadedly mounted to the bolt 74. A spring member 70 is mounted to the bolt 74 and supported on cone-shaped surface of the first pushing member 77. Two spring washers 73 are mounted on the spring member 70 and a second cone-shaped pushing member 710 is mounted on the bolt 74 and engaged with a recessed portion 71 of the spring member 70. A spring 76 is biased between the disk 75 and the second pushing member 710. When rotating the bolt 74, the first pushing member 77 is moved upward to expand the spring member 70 and the handlebar stem 13 is moved downward to push the pressing ring 78 to position the upper head set 400. However, the conventional way to position the head set 400 requires too many parts and it takes a lot of time to assemble them.
In accordance with one aspect of the present invention, there is provided a head set positioning device which comprises a positioning tube movably extending through a crown portion of a front fork and having a rack portion defined in an outer periphery of the positioning tube. A lower head set is fixedly mounted to the positioning tube and a lower end of a head tube is fixedly connected to the lower head set. An upper head set is fixedly connected to an upper end of the head tube and the positioning tube extends through the upper head set. A handlebar stem is mounted to the positioning tube and an extension tube extends from the handlebar stem. A through hole is defined through the handlebar stem. A carry tube is received in the extension tube and located transverse to a longitudinal axis of the extension tube. An aperture is defined through the carry tube and communicates with the through hole. A gear member is rotatably received in the carry tube and engaged with the rack portion in the positioning tube via the aperture and the through hole. A holding member is engaged with the gear member.
The primary object of the present invention is to provide a head set positioning device that employs rack portion and gear member to pull the handlebar stem downward to position the upper head set and the lower head set.